California Democratic Rep. Loretta Sanchez said on Thursday evening that her claims about the percentage of Muslims "who have a desire for a caliphate and to institute that in anyway possible" came from a book "published by the Harvard Press."

"Actually, it's in a book that I read published by the Harvard Press," Sanchez, who is running for Barbara Boxer's Senate seat, said on PBS. "But, you know, think about this: what I'm talking is about Muslims around the world. And, um, I think that that is a high number and if you see the rest of the interview that I have, I think that is a very big number, between 5 and 20% of Muslims who have this idea to build a caliphate, and yes, a few Muslims are willing to use violence."

A Sanchez spokesperson did not respond to e-mails from BuzzFeed News asking what book Rep. Sanchez was referring to. In her original comments, made on "PoliticKING with Larry King," Sanchez said the figures came "from the people that I speak to."

In that interview, Sanchez said, "But certainly, we know that there is a small group, and we don't know how big that is — it can be anywhere between 5 and 20%, from the people that I speak to — that Islam is their religion and who have a desire for a caliphate and to institute that in anyway possible, and in particular go after what they consider Western norms — our way of life."

She went to say, "And again, I don't know how big that is, and depending on who you talk to, but they are certainly — they are willing to go to extremes. They are willing to use and they do use terrorism."

A Harvard University Press spokesperson suggested that the book Sanchez mentioned might be Islam and the Future of Tolerance: A Dialogue, co-written by Sam Harris and Maajid Nawaz. She included an excerpt from the book in which the authors speculate about the percentage of Muslims worldwide who are "Islamists," a term defined earlier in the book as "the ideology that seeks to impose any version of Islam over society." Islamism is presented as distinct from "jihadism," which is defined as "the use of force to spread Islamism."

In the passage sent by the Harvard University Press spokesperson, Harris, one of the authors, estimates that the global proportion of Muslims who are Islamists "is probably around 20 percent," also saying that "poll results on the topic of shari'ah generally show much higher levels of support for its implementation."

Nawaz, for his part, argues that, globally, Islamism is "probably less popular in other Muslim-majority societies" than in Egypt where, he writes, it "could gain only 25 percent in the first round of elections."

"This is what my gut tells me; I have no empirical evidence," Nawaz adds.

On Thursday night, Sanchez issued a statement to BuzzFeed News, saying, ""I strongly support the Muslim community in America and believe that the overwhelming majority of Muslims do not support terrorism or ISIS. We must enlist the voices of the Muslim community in our fight against ISIS instead of alienating them through fear-mongering and discrimination."

Christopher Massie is a political reporter for BuzzFeed News and is based in New York.